In general, the video signals of TV and DVD video are interlaced, and are not progressive as in the computer monitor display. There are two fields in the interlaced scanning. The odd scan lines form one field and the even scan lines form another field. And, the TV controller uses these two fields to show the TV video signals onto the TV screen. If the TV screen is a CRT display, due to the material characteristics of it, the display between pixels and pixels will be overlapped when electron beam hits onto the surface (phosphorus), so the sawtooth on the screen will be fogged and still looked smooth; also, due to the persistence of vision and the response time with human's vision, the flicker generated by the display screen will not be very conspicuous for enough distance (human's vision is very easy to sense the flicker of big area but not a small area).
Because of the developing technologies progress of digital system and flat panel, lots of products with flat panels are well implemented, such as flat TV, LCD monitors, etc. Because of the material issues of panel, the characteristics of display with flat panel are quite different from the traditional CRT monitor (such as the response time, the there is no overlapped characteristic between pixels and pixels under displaying). Whenever a video is displayed onto the flat panel, the artifacts will be much more conspicuous than displayed onto the CRT monitor, such as sawtooth, serration, and judder, etc. Furthermore, the above disadvantages will be more and more conspicuous when the panel size getting bigger and bigger. Therefore, in order to obtain a better display quality, most likely the TV video signal will not be displayed onto the flat panel until a de-interlacing is processed. So, designing a good de-interlacer for the LCD TV becomes a very important task.
The frame buffer structure for a typical de-interlacing process is shown as FIG. 1, which can be used to detect and calculate the target point X by three fields F2, F1, and F0. F1, F2, and F0 are interlaced fields mutually, the neighbored pixels C, D, M, N, P, and Q of target pixel X are located in the F1 field (target field); the neighbored pixels B, F, H, J, and L of target pixel X are located in the F2 field, which is in front of the F1 field; and the neighbored pixels A, E, G, I, and K of target pixel X are located in the F0 field, which is behind the F1 field. But, if the video signal contains stationary and motion video pixels concurrently (such as stationary caption and motion background), and if the stationary video is displayed for a period of time, then the typical de-interlacing technology which only refers to three or four fields will not be enough and efficient to separate the motion and stationary video pixels from the video signals. Increasing the reference fields will improve this problem for having more temporal information, but will also increase the requirement of memory bandwidth, and this is a problem for hardware implementation. In this invention, we propose a method which can keep up to seven fields temporal information while only needs three fields bandwidth by using the fields' differences storing back method. And, by incorporating with the spatial domain patterns, the correct rate of motion detection for several of video combinations can be further enhanced.